When producing objects consisting of bigger units, which shall be sealingly interconnected, sealing agents are widely used in the form of especially developed qualities of putty. For this purpose putties have been developed with a substantial ability to penetrate into even very small spaces and joints and thereby form a continuous sealing layer which is resistant to chemical as well as mechanical influence.
It thereby has been possible to attain considerable profits. At manufacture e.g. of car bodies it thus has been possible to abandon the method of tight welding entire joints and instead to use spot welding for interconnecting the car body parts, and then a special putty under high pressure is pressed into the joints.
The demands placed upon such a putty are of course very large. The viscosity at the moment of application as well as the homogenity of the material are thereby of crucial importance. For this reason, as an example, in the just mentioned application of the putty permitted temperature tolerance of the putty thus is .+-.0.5.degree. C. only. It certainly has been possible, fairly to hold such a temperature, but the problem has been to obtain also a sufficient homogenity in combination with a rational manufacture.
In a known device the putty is pumped from a drum and is pressed through a heated pipe. This will cause the phenomenon that putty, due to the friction, as a thin surface layer will adhere to the inner envelope surface of the pipe and become immobile. This layer will solidify and build up radially inwards so that the flow area gradually will be reduced and finally becomes so small that the process must be interrupted and a time-wasting cleaning operation must be begun.
Another drawback is that the components of the putty on its path from the drum to the putty gun are separated, which refers particularly to bonding agents therein, which means that some putty portions will contain too much and other too little bonding agent.
In DE-A-2364500 is shown a combined heat exchanger and static mixer for photographic emulsions, which shall have a temperature between 35.degree. and 40.degree. C. The device consists of an outer tube and an inner pipe extending axially therethrough, which inner pipe has external helically extending segments. The heating medium flows through the inner pipe, whereas the emulsion passes between the inner pipe and the outer tube and the helically extending segments afford the emulsion a helical path. A temperature tolerance as low as 0.5.degree. C., which is permitted for putty is considered to be difficult to maintain with this device.